The keys were placed in a massive "flock" within the third of the Stone's Chambers, and only one of them would allow entry into the fourth chamber through a locked door that was made impervious to Unlocking Charms. The chamber also contained brooms, which could be used to retrieve the correct key, though the keys would scatter chaotically as soon as the brooms were used to lift-off.

The third of the Underground Chambers was filled with the winged keys, which at first appeared to be birds. As they soon discovered the locked door at the end of the room was impervious to the Unlocking Charm (Alohomora), they also realised the keys were not, in fact, birds.

Hermione cleverly deduced that the key that would open the locked door must be an old one to match the old lock on the door, and the only old key was one with a broken wing, as it had just been used by Quirinus Quirrell. As soon as Harry, Ron and Hermione took off on brooms to catch the "old key," they rest of the keys started zooming and darting all over the place. The winged key that was able to open the locked door was described as an old-fashioned silver key with bright blue wings.

Behind the Scenes

by Clare Melinsky

In the novel, each one of the Trio seized a broomstick and kicked off into the air to catch the winged key, while in the film, only Harry used a broomstick to catch the key.

In the film adaptation, (most of) the keys swarm and attack Harry as soon as he touches the broom, which does not happen in the book.